Fabrication of an object of complex configuration from an aluminum alloy is facilitated by closed-die forging of a billet of the alloy to produce a near-netshape, which then requires only minimal machine finishing to acquire a final shape. The forging process permits control of meta flow, and thereby permits control of the formation of metallurgical microstructures in localized areas so that directional properties of the crystal structure of the alloy can be made to conform to directional requirements of the particular application intended for the object being fabricated.
In the prior art, forging procedures for aluminum alloys were formulated primarily to achieve specific geometrical configurations, and were not generally designed for maximum efficiency in process scheduling or for obtaining optimum mechanical properties in the objects being fabricated. In the prior art, a forging schedule for an aluminum alloy typically included multiple forging sequences, intermediate stage reheating, a sizing or coining operation (depending upon the size and complexity of the object being fabricated), and a final heat-treatment sequence for thermal strengthening of the object.
Forging of an aluminum alloy is conventionally performed in a heated die at a temperature in the 370.degree. C. to 470.degree. C. range. If the alloy is of the precipitation-hardenable type (e.g., an aluminium alloy of the 2000, 6000 or 7000 series as described in standard texts such as Alcoa Aluminum Handbook, Second Edition, Aluminum Company of America, Pittsburgh, Pa. (1962)), the final heat-treatment sequence conventionally requires "aging" of the forged object at a temperature in the 120.degree. C. to 200.degree. C. range for a relatively long period of time, i.e., typically from 8 to 36 hours.